This invention relates to optical stabilizers for damping ambient vibrations from optical instruments such as mirrors, hand held telescopes of high power and other light deflective devices. More particularly, the present invention relates to a hydrostatically supported optical instrument which is proportionally fluid coupled to a reference coordinate system or orientation in space during instrument vibration. Several embodiments of the invention are disclosed. In a first embodiment, the relationship between the placement of the stabilizer in the optical train, the power of the optical train, and the proportional couple of a mirror to space is disclosed. In another embodiment, the relationship between the power of a telescope, the index of refraction of the fluid bath, the power of the remainder of the optical train and the proportional couple of the telescope to a reference coordinate system is disclosed.
It is already known to inertially stabilize a two-power optical train by placing a stabilized mirror between the objective lens and the imaging plane of an instrument. Moreover, such mirrors, typically supported in fluid filled chambers, remain stationary with respect to space when the instrument undergoes vibration or rapid angular movement (as distinguished from panning). (See my U.S. Pat. No. 3,532,409 entitled "HYDROSTATICALLY SUPPORTED OPTICAL STABILIZER" issued Oct. 6, 1970).
An object of the present invention is to provide a space referenced couple through fluid between a mirror on one hand and the chamber sidewalls on the other hand so that the mirror undergoes a proportional movement with reference to space when the chamber is moved with reference to space. By selecting the optics of the immersed telescope and the indices of refraction of the fluid bath, stabilizing image deflection can be obtained.
An advantage of this invention is that the stabilizer can be used with optical instruments having a wide variety of design configurations.
An additional advantage of this invention is that where powers of greater than two are desired, a two-power imaging optical train followed by a higher powered viewing optical train is not required. The number of positive lenses used is thus reduced with resultant reduction of curvature of field and chromatic aberrations.
An additional object of this invention is to utilize the index of refraction of the mirror supporting fluid to obtain the desired angular reflection of the stabilized light.
An advantage of utilizing this index of refraction is that even in the case where the optical instrument remains stationary with respect to a spatial reference during angular movement of the chamber in space, the indices of refraction can be used to increase the deflection generated by the motion of the casing containing the optical instrument.
An additional object of this invention is to disclose a series of optical instrument and chamber configurations where the resultant fluid couple will permit the stabilizer to be mounted at locations off of the midpoint between an objective lens and imaging point along an optical train.
An advantage of this controllable fluid couple is that the stabilizer can be located to complement the design of the optical path. Optical path dimensioning relative to the location of the stabilizer is no longer required.
A further object of this invention is to provide an optical instrument and chamber fluid couple where the optical instrument moves at a rate proportional and opposite to the angular vibrational rate of the chamber with respect to an orientation in space. This can be achieved by constructing a chamber with an elongate section along the optical axis through the chamber.
An advantage of this optical design is that a mirror can be placed relatively close to the focal plane or eyepiece of the stabilized instrument.
A further object of the invention is to provide an optical instrument and chamber fluid couple where the optical instrument moves at a rate in the same sense and less than the angular vibrational rate of the chamber with respect to an orientation in space. This can be achieved by constructing a chamber with an elongate section normal to the optic axis of the optical instrument.
An advantage of this configuration is that a mirror can be placed in a position adjacent the objective lens. In this location, small mirror movement produces large corresponding image stabilizing movement.
A further advantage of this chamber construction is that the small mirror movement giving large corresponding image stabilizing movement produces less inclination of the image plane with resultant reductions in distortion during instrument image stabilization.
A further object of this invention is to athermalize the focal length of the optical path between the objective and imaging plane. Accordingly, a small positive lens of fluid is provided.
An advantage of this fluid lens construction is that when thermal changes in the index of refraction of the supporting fluid occurs, the fluid lens produces complementary changes stabilizing the position of the image plane with respect to the chamber and objective.
A further advantage of this invention is that the couple between the chamber on one hand and the optical instrument on the other hand will permit numerous chamber configurations, which configurations can be other than spherical and can be changed to accommodate many preselected optical housings.
An additional advantage of this invention is that for relatively large degrees of telescope motion, equal and opposite optical wedges are generated along the light path between the end of each window and the immersed telescope; a partial chromatic correction results.
An advantage of forming the optical wedges from the glass of the fluid chamber windows is that higher indices of refraction may be used. The inherent limitation of a relatively low index of refraction common with most usable transparent liquids is avoided.
Yet another advantage of forming the optical wedges in the glass window is that light deflection can be made to occur at one window and not at the remaining window. With this configuration more convenient and suitable optic powers can be used for the immersed telescope.
Still another advantage of generating the optic wedges in the glass of the chamber windows is that the effect on a liquid of temperature changes, viscosity changes and surface effects can be minimized. A gaseous fluid, such as in air, can be used.
A further advantage of this invention is that the stabilization is relatively insensitive to translational errors of the telescope along the optic path.
Yet another advantage of this invention is that a telescope of simple construction can be readily designed for being immersed in a fluid filled chamber.
Yet another advantage of one embodiment of this invention is that the surfaces of the window in the chamber as well as some of the lenses of the telescope can all be substantially planar. With this construction optical problems created at the interface between the fluid bath and the window and lenses are minimized.
Still another advantage of the stabilizer of this invention is that it can be mounted at a wide range of locations along the optical axis of the stabilized telescope.
Yet another advantage of the stabilizer of this invention is that it can be easily adapted for use with optical image inversion and displacement devices, and also with relay optics.
Other objects, features, and advantages of this invention will be more apparent after referring to the following specification in conjunction with the attached drawings.